Knock off a few TODOs

doc/messaging/notes.txt

@@ -1,14 +1,10 @@
 
 TODO:
 
-  - can_send_version() in RPCClient
-
   - we need some way for the dispatcher to take the incoming
     context dict and instantiate a user-supplied request context
     object with it
 
-  - notifications!
-
   - @expose decorator
 
   - when shutting down a dispatcher, do we need to invoke
@@ -17,8 +13,6 @@ TODO:
   - ClientException - e.g. the executor should handle this being
     raised by the dispatcher
 
-  - raising Timeout when a reply isn't received
-
   - the InvalidTarget checks seem like they're generic preconditions
     that all drivers would want enforced
 
@@ -30,9 +24,6 @@ TODO:
     sure the context of the currently dispatching rpc is available to
     logging. Need to abstract out the dependency on eventlet for this.
 
-  - the current rpc code dispatches each method in its own greenlet,
-    we need to do the same in the eventlet executor
-
   - I'm not sure listener.done() is really needed - can't we ack the
     message before returning it from poll() ?